If the sides of a triangle are 56cm, 60 cm and 52cm long, then its area is

$b$ $=$ 60 cm

$c=$ 52 cm

$s=\frac{a+b+c}{2}=\frac{56+60+52}{2}=\frac{168}{2}$ $=84$ cm

Area $=\sqrt{s\times \left(s-a\right)\times \left(s-b\right)\times \left(s-c\right)}$

$=\sqrt{84\times \left(84-56\right)\times \left(84-60\right)\times \left(84-52\right)}$

$=\sqrt{84\times 28\times 24\times 32}$

$=\sqrt{12\times 7\times 4\times 7\times 4\times 6\times 16\times 2}$

$=\sqrt{2\times 6\times 7\times 4\times 7\times 4\times 6\times 16\times 2}$

$=2\times 6\times 7\times 4\times 4$

$=1344{\text{ cm}}^2$